1. Field
The present disclosure relates generally to electronics, and more specifically to transmitters and receivers.
2. Background
In a radio frequency (RF) transceiver, a communication signal is developed, upconverted, amplified and transmitted by a transmitter and is received, amplified, downconverted and recovered by a receiver. In the receiver, the communication signal is typically received and downconverted by receive circuitry including a filter, an amplifier, a mixer, and other components, to recover the information contained in the communication signal. A single transmitter or receiver can be configured to operate using multiple transmit frequencies and/or multiple receive frequencies. For a receiver to be able to simultaneously receive two or more receive signals, the concurrent operation of two or more receive paths is used. Such systems are sometimes referred to as “carrier-aggregation” (CA) systems. The term “carrier-aggregation” may refer to systems that include inter-band carrier aggregation (Inter-CA) and intra-band carrier aggregation (Intra-CA). Intra-CA refers to the processing of two or more separate (either contiguous or non-contiguous) carrier signals that occur in the same communication band. The carrier aggregated RF signal is typically down-converted using two or more distinct local oscillator (LO) frequencies, which generally employs a low noise amplifier (LNA) having a single RF input and multiple RF outputs to process the multiple carriers present in the Intra-CA RF signal. State-of-the art LNAs use a cascode device diverter switching architecture to support Intra-CA, but such an architecture consumes a large amount of current when supporting multiple carriers, and becomes impractical for three or more carrier signals.
Therefore, in Intra-CA receiver systems, it would be desirable to reduce the amount of current consumed by the LNA when operating on multiple carrier signals.